Fluid couplings wherein the male and female parts are interconnected solely by axial displacement of the parts have the advantage of permitting the parts to be very quickly coupled, and such couplings are often described as "push-to-connect" couplings. In such couplings a shoulder is usually defined upon the male part engaging with a retainer, often resilient spring fingers, mounted on the female part which engage the male part shoulder upon the parts being fully coupled.
While such couplings using spring biased fingers or clips are capable of producing a fluid-tight connection quickly, disadvantages occur when the parts are separated. To separate couplings utilizing spring finger retainers the fingers must be removed from the male part shoulder, and such occurrence removes any restraint against separation of the coupling parts. If the fluid system in which a coupling is utilized is under pressure during uncoupling the parts will blow apart producing a dangerous condition with respect to the safety of the operator, and there is need for a push-to-connect coupling which controls the axial position of the coupling parts during separation thereof.
It is an object of the invention to provide a fluid coupling having male and female parts wherein the parts may be coupled using an axial push-to-connect movement, and yet separation of the parts is positively controlled and the parts cannot be rapidly forced apart even if the fluid system is under pressure.
Another object of the invention is to provide a combination push-to-connect and threaded nut coupling wherein initial connection and communication between the parts occurs by axial displacement of the parts and final connection, and separation of the parts, is controlled by a threaded nut type lock.
Another object of the invention is to provide a concise fluid coupling having the advantages of a push-to-connect coupling motion and the advantages of a nut controlled separation of the coupling parts.
In the practice of the invention a female coupling part includes a passage which receives the nose of the male part. Elastomeric sealing rings interposed between the parts produces fluid-tight sealing when the parts are fully coupled. The female part includes exterior threads receiving a nut having a radially depending flange in which a central opening is defined through which the male part is inserted. The male part includes a radial shoulder defined thereon axially set back from the nose and this shoulder, when the parts are fully coupled, is located in substantial radial alignment with the open end of the female part.
A radially expandable and contractible retainer in the form of a ring is located between the open end of the female part body and the nut flange. This ring is engaged by the male part shoulder during insertion of the male part through the nut flange opening and expands to permit the shoulder to pass therethrough. Once the shoulder passes through the retainer the retainer contracts to engage the back side of the shoulder, and the diameter of the retainer is larger than the flange central opening such that the opposite end of the retainer will engage the inside surface of the nut flange.
The retainer and nut will prevent withdrawal of the male part from the female part passage, and withdrawal is only permitted as the nut is unthreaded with respect to the female part. Thus, with a pressurized system the internal force acting upon the coupling parts tending to separate them is resisted by the retainer and nut and control of the separation of the parts is determined by the axial position of the nut on the female part.
The use of the invention permits the coupling parts to be slowly separated, and if the fluid coupling is being used in a pressurized circuit, for instance, such as found in refrigerators or air conditioners, the parts may be permitted to separate sufficiently to break the seal and permit the circuit to bleed and depressurize prior to the coupling parts being fully disconnected.
In an embodiment of the invention particularly suitable for low-pressure fluid circuits, the sealing rings are mounted upon the nose of the male part, and a second shoulder is defined upon the male part having an outer diameter greater than the diameter of the nut flange central opening. Thus, unthreading of the nut causes the flange to engage the male part second shoulder and mechanically withdraws the male part from the female part passage as the nut is unthreaded. As the retainer is of a flexible nature with respect to radial deformation the components of the coupling may be reused innumerable times without damage or significant wear thereto .